The major objective of this research program is to ascertain by field studies the reasons for geographic differences in mortality and incidence of cerebrovascular disease in the United States as well as for the differences between blacks and whites. Examination of population samples in high, intermediate and low mortality areas in the United States will be carried out to determine whether there are differences in the frequency of such risk factors as elevated blood pressure, cholesterol, etc. In addition, a prospective mortality study of veterans will be carried out to determine whether cross-sectional differences in mortality are also present in prospective mortality analyses.